A. Field of the Invention
The present invention relates to electrical junction boxes which are known as pull boxes which are used to enclose interconnections between electrical power mains cables and electrical power distribution cables to devices such as municipal and highway street lighting fixtures, traffic signals and the like. More particularly, the invention relates to a novel cover lid, kit and method for upgrading existing pull boxes used for street lighting which include a concrete vault that is buried in the ground near a light standard for providing power to a street or highway light, the cover lid having a novel construction which thwarts unauthorized access to the interior of the pull box to thus protect against theft of copper wire cables leading into and out of the pull box.
B. Description of Background Art
Electrical junction boxes are used widely to connect electrical power input cables of street lights installed along streets and highways to electrical power mains. Such junction boxes, for reasons which will become apparent from the following discussion, are typically referred to as pull boxes. The pull boxes are typically installed in shallow pits dug into the ground, and have generally the form of a rectangular ring-shaped concrete shell. The open bottom of the shell is fitted down into a pit which has been dug into the ground and has two or more conduits that protrude upwardly from the bottom of the pit. The conduits have protruding outwardly from open upper ends thereof insulated electrical power line cables which are strung through the bores of the conduits, and include a power source conduit that contains cables which are connected at distal ends thereof to a power pole or other source of electrical power, and pulled through the conduit, which is horizontally disposed under the ground. The pull box pit also has a second conduit which is disposed between the pit and a destination requiring electrical power, such as a street light or highway lighting fixture.
Within the hollow, interior vault-like space of the pull box shell, electrical interconnections or splices are made between power mains conductors and conductors leading to a lighting fixture or other electrical power consuming device. Usually, the interconnections include high-current fuses. After interconnecting splices have been made between power mains conductors and power distribution conductors which extend out through the exit conduit to the street light or other electrical device, a cover lid is installed on the pull box.
Pull boxes of the type described above are used extensively for such applications as providing electrical power to a row of light standards used to illuminate a street or highway. In such applications, electrical power from a power line main located near one of the light standards is supplied to a first light standard through electrical interconnections made between power cables entering the pull box through a first, power mains source conduit and supply cables to the light standard exiting the pull box through a second, feeder conduit disposed between the pull box and the first light standard.
In a typical power distribution arrangement for a row of street or highway light standards, a first pull box which provides power to a first light standard in a row or chain, also has protruding into the interior space at the end of a third conduit which contains electrical wires that are disposed through the third conduit which runs under the surface of the ground to a second pull box located near a second light standard in a row of light standards.
Electrical connections are also made in the first pull box between the power mains cables and the cables leading to the second pull box, thus providing electrical power from the mains to the second light fixture.
In this way, electrical power from a single power mains source is provided to a row of street lighting fixtures in a series of pull boxes containing interconnected electrical wires in an arrangement sometimes referred to as a “daisy chain.”
Although the daisy chain power distribution arrangement of pull boxes described above is straight forward and efficient, problems have recently arisen when the arrangement is implemented with existing pull boxes, for the following reasons.
In recent years, the price of copper has risen sharply, from a cost of one dollar US per pound in December 2008 to four dollars and fifty cents US per pound in 2011. Because of the steep rise in the price of copper as a commodity, thieves have been incentivized to engage in theft of copper wire which is then sold to scrap dealers.
One technique for stealing copper wire which has gained in popularity with thieves involves removing the lid of any pull box in a daisy-chain of pull boxes, removing the lid from an adjacent pull box in a daisy chain, freeing the ends of the wires in both pull boxes by cutting the wires, and pulling the freed lengths of wires out of one or the other of the pull boxes. There have been several well documented cases in the United States where thieves who made the initial cuts in daisy-chain power cables, apparently oblivious to the fact that cables carried electrical power, were incinerated for their efforts.
In response to the problem of dangers to the public resulting from the loss of street or highway lighting because of theft of copper wire used to supply power to the lights, the present inventor invented a security enclosure for pull boxes. That prior-art security enclosure has various security measures which thwart access to wire cables contained within the enclosure, and has proved to substantially reduce theft of wire from pull boxes fitted with the security enclosures. However, as the price of copper has continued to rise, copper-wire thieves have gotten more aggressive, and have sometimes been able to breach the security features of presently manufactured and marketed security enclosures. Accordingly, the present inventor has been motivated to develop a wire theft protection enclosure which provides even greater protection than prior art devices.